1. Field of the Invention
This invention relates to non-phosphate built heavy duty laundry detergents. More particularly, this invention relates to a non-phosphate builder detergent utilizing a builder system comprising a citrate salt and mixture of an alkali metal silicate and an alkali metal carbonate.
2. Discussion of the Prior Art
Public awareness of the importance of improving the environment and avoiding disruptive effects on the ecology has been increasing greatly, and as a result thereof, widespread re-examinations of waste disposal methods have been undertaken. From various studies of our lakes, rivers, streams and ground waters, it has been concluded by some that ordinary household detergents, especially those comprising long lasting synthetic organic detergents and phosphate builders, have had detrimental effects on such waters. The surface active organic compounds which are not readily decomposed after discharge from the sink, wash tube or washing machine, may find their way into natural streams, creeks, rivers and lakes.
The major detergent manufacturers are endeavoring to remove from their products long lasting synthetic organic detergents, such as the highly branched alkyl aryl sulfonates, which are non-biodegradable, and have replaced these with comparatively easily degradable straight chain alkyl benzene sulfonates or similar materials which will be destroyed in a short time.
Because of the very desirable building, sequestering and soil-suspending activities of the polyphosphates, especially the alkali metal tripolyphosphates and pyrophosphates, it has previously been difficult to eliminate them from detergent compositions without significant losses in cleaning power. Even 100% active synthetic organic detergents have not been able to produce the same cleaning effect as is obtained from combinations of such compounds and polyphosphate(s). At the present time, about the only substitute in part for the polyphosphates which appears to be able to duplicate their effects substantially is nitrolotriacetic acid or a corresponding nitrilotriacetate, which are often referred to as NTA. However, recent laboratory tests and scientific studies have indicated that NTA might be a harmful factor as a cause of cancer and accordingly, there have been strict Government regulations prohibiting or limiting its use. Therefore, to overcome these deletorious effects on the environment caused by the use of phosphates and nitrogen compounds in laundry products, there is great activity in providing effective, safe and acceptable detergent compositions which do not contain phosphate or nitrogen compounds as a builder. The present invention is directed to such compositions.